/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.skatiger.jrove.servlet;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;


public final class RequestHeaderValuesMap extends AbstractAttributeMap<String[]> {
    private final HttpServletRequest _httpServletRequest;
    private final Map<String, String[]> _valueCache = new HashMap<String, String[]>();

    RequestHeaderValuesMap(final HttpServletRequest httpServletRequest) {
        _httpServletRequest = httpServletRequest;
    }

    @SuppressWarnings("unchecked")
    protected String[] getAttribute(final String key) {
        String[] ret = _valueCache.get(key);
        if (ret == null) {
            ret = toArray(_httpServletRequest.getHeaders(key));
            _valueCache.put(key, ret);
        }

        return ret;
    }

    @SuppressWarnings("unchecked")
    protected Enumeration<String> getAttributeNames() {
        return _httpServletRequest.getHeaderNames();
    }

    protected void removeAttribute(final String key) {
        throw new UnsupportedOperationException("Cannot remove HttpServletRequest HeaderValues");
    }

    protected void setAttribute(final String key, final String[] value) {
        throw new UnsupportedOperationException("Cannot set HttpServletRequest HeaderValues");
    }

    private String[] toArray(Enumeration<String> e) {
        List<String> ret = new ArrayList<String>();

        while (e.hasMoreElements()) {
            ret.add(e.nextElement());
        }

        return ret.toArray(new String[ret.size()]);
    }
}